1. Field of the Invention
The present invention relates to a propulsion assembly having elongate members. In particular, it relates to a propulsion assembly having elongate members as used in bicycles.
2. Description of the Related Art
The concept of using reciprocating elongate members for propelling a bicycle is known. For example, Canadian Patent No. 2,120,535 to Rakocevic shows a pair of elongate members that extend past the rear of the rear wheel to a clutch system using two chains. The clutch system is supported by a long, curved tube which extends back from the frame and around the rear wheel. While the bicycle in Rakocevic provides relatively long elongate members, it is unclear whether the bicycle with its curved tube is sufficiently stable to function properly. Also, the bicycle in Rakocevic suffers the disadvantage of requiring a number of exposed parts, including two chains and cables which may be prone to entanglement and failure. Moreover, while bicyclists are accustomed to circular motion when pedalling, the bicycle in Rakocevic requires a user to pedal it in an ungainly up and down manner.
The idea of using elongate members in combination with a ratchet system for bicycles per se is also known. U.S. Pat. No. 3,881,747 to Abbott shows a bicycle foot pedal that is movable through an adjustable linkage of elongate members. The elongate members are in the form of levers for transmitting one-way rotational power to an elevated drive sprocket. However, Abbott splits the elongate members into two articulated portions and as a result the propulsion system provides a diminished leverage or torque. Abbott also requires for its propulsion system a bicycle that is highly modified. Lastly, the bicycle in Abbott requires the user to pedal it in an unconventional, primarily up and down manner.